This invention relates to apparatus for frying foods and particularly to improved deep fat fryers wherein the fat is circulated and filtered.
Deep fat frying of foods such as potatoes, meats, fish and pastries is performed by immersing the foods in a vessel containing heated cooking oil or fat. Of considerable importance in such fryers are their systems for heating the fat and for maintaining its temperature uniformity and cleanliness.
Heating systems of deep fat fryers are generally of three types. Some heaters comprise gas-fired burner tubes or electric elements immersed in fat held within the fryer vessel. A second category of fryer heaters includes systems which apply heat to fat in the fryer vessel by exposing the vessel to combustion gases or the condensible vapors of a heat pipe working fluid. A third type of heater includes a heat exchanger external to the fryer vessel through which fat is circulated, sometimes after passage through a filter.
Present deep fat fryers have one or more drawbacks or undesirable aspects. For example, commercially available fryers have relatively low efficiencies and, if gas-fired, have high flue losses. Typical calorimetric efficiencies for available gas-fired fryers are in the range of 40-60 percent.
Prior art fryers which circulate fat for external heating may utilize substantial energy in pumping the fat, particularly if a filter is included in the circulation system. Replacement or cleaning of filters in such units can be difficult, messy, and time-consuming, and clogging or blockage of the filters requires an immediate shutdown of the fryer.
It is a primary object of the invention to provide a deep fat fryer with an improved filtration system.
It is an object of the invention to provide a deep fat fryer with filtration whose filter minimizes risk of leakage of cooking fat during operation of the fryer and changing of the filter element.
It is also an object of the invention to provide a deep fat fryer whose filter element may be easily changed without the use of shutoff valves or the need to drain the fryer tank.